I'm pretty sure there aren't any nutrients in pith.

Haruhi (and Kyon) are playing a traditional new year's card matching game called Karuta.
There are various styles of decks, from something as simple as a set with half of the cards displaying a letter and the other half display an image of an object beginning with that letter, to ones where half have the first half of a verse of poetry, and the other half have the second half of the verse.

Ah, I thought it was cards as in thank you or happy birthday or etc sort of cards, I forget what they're collectively called.
But Kyon eating sherbet(?) is unrelated, right?

Alignn said:
Ah, I thought it was cards as in thank you or happy birthday or etc sort of cards, I forget what they're collectively called.
But Kyon eating sherbet(?) is unrelated, right?

Unrelated to the cards yes. These are all typical New Year's activities. Eating mikan, eating shaved ice, playing karuta.

Pith is designed to store vitamins actually.

I still pass on eating it though. Other, better ways to get them.